1. Field of the Invention
The invention relates to a heat-dissipating device, and particularly to a heat-dissipating device adapted to a projection display apparatus with an air outlet.
2. Description of the Related Art
FIG. 1 shows a schematic diagram illustrating a partial structure of a conventional projection display apparatus. Referring to FIG. 1, the projection display apparatus 100 uses a high-power lamp 102 as a light source. Since the high-power lamp 102 generates considerable heat during operation, a fan 104 is disposed near the lamp 102 to induce a forced convection of air, and the flow W flows through the lamp 102 and leaves by an air outlet WP to cool down the lamp 102. As shown in FIG. 1, a fixed louvered fence 106 also constituting part of a housing of the projection display apparatus 100 is disposed at the air outlet WP. The fixed louvered fence 106 includes multiple guiding plates 108 parallel to each other, and the flow W comes out of the projection display apparatus 100 via each opening formed between two adjacent guiding plates 108. The guiding plates 108 are properly inclined to block out dazzle of the high-power lamp 102 and disturbed heat flows to maintain high projection quality. However, since the size of an opening formed between two adjacent immobile guiding plates 108 is not adjustable, containments such as dust are liable to enter the inside of the projection display apparatus to reduce the operation life and the projection performance. Besides, the fixed size of each opening results in unchanged flow resistance, and the flow resistance is not further reduced. In that case, the fan speed is forced to increase greatly under high-temperature circumstances to create a lot of noises and increase power dissipation.